From the 2D plane image and the 3D plane image to the 3D stereo image, the computer user's request for image quality is getting higher and higher. Since human beings have two eyes observing object independently, human beings can see the stereo object. The view angles of two eyes are different so that the images two eyes respectively observe are different. After images fusing by the brain, human beings can see the stereo image. Hereinafter, “stereo” of image means the depth and solidity of the image.
As shown in FIG. 1, in a computer plane 3D graphics system, the AGP or PCI bus 4 transmits the 2D or 3D graphics command to the 3D graphics engine 5. The Digital-Analog Converter 7 displays the analog signal converted from the digital signal of the image on the monitor. The 3D graphics system further includes a graphics memory 3 and a memory controller 8.
FIG. 2 discloses a stereo 3D image system. Similarly, the stereo image system includes a 3D graphics engine 5 for receiving the graphics command from the AGP or PCI bus 4. The 3D graphics engine 5 transmits the image data through the Digital-Analog Converter 7 to the timing controller 6, and displays the image on the monitor. The difference between the stereo 3D image system and the plane 3D image system is that the image of the stereo 3D image system includes a left eye image 31 and a right eye image 32. The stereo 3D image system simulates the different view angles of two eyes observing objects to produce the different left eye image 31 and the right eye image 32. The left eye image 31 and the right eye image 32 are stored in the graphics memory. The stereo 3D image system lets the left eye see the left eye image 31 only and lets the right eye see the right eye image 32 only by using a synchronized signal.
Since human beings have two eyes and there is only one monitor, human beings can't see the effect of stereo image on the monitor. The method to solve this problem is to group the images respectively observed by the right eye and by the left eye and alternately displaying the images for right and left eye on the monitor. And the images are viewed through a synchronized shutter viewer (shutter classes). The working principle of the shutter glasses is to mask the right eye while the monitor is displaying the left eye image, and to mask the left eye while the monitor is displaying the right eye image. Due to the fast alternate display of images on the monitor and the image-residual of vision of human beings, human beings' brain generates stereo vision. The stereo 3D image system determines when to display the left image 31 and the right image 32 using a memory controller 8.
In addition, as shown in FIG. 3, a 3D graphics engine 5 in another stereo 3D image system receives the graphics command from the AGP or PCI bus, transmits the image data to the CRT timing controller 6 and the digital-analog converter 7 and displays the image on the monitor. But in this stereo 3D image system, a red-blue glasses 27 replaces the shutter glasses 25. The stereo 3D system reddens one of the right eye image and the left eye image by filtering the blue light and the green light, and blues the other image of the right eye image and left eye image by filtering the red light. Through the red glass of the red-blue glasses allowing red light passing, only the red image can be seen. Through the blue glass of the red-blue glasses allowing blue light and green light passing, only the blue image and green image can be seen. So that humans' view can respectively focuses on the left image 31 and the right image 32.
FIG. 4 shows the different offsets of the left eye image and right eye image projected on the projection plane. The left eye image and the right eye image are located at different depth positions. Because the object 11 in the CRT space 46 and the object 21 in the viewer space 45 project the image 10 at the same position without stereo effect, a viewer observing the image in the original center line 40 can't see the stereo effect of the objects. When observing the object 11 in the CRT space 46, the object 11 projects a left image 12 in left side of the projection plane 44 to be observed by the left eye 42. The object 11 projects a left image 13 in right side of the projection plane 44 to be observed by the right eye 43. When observing the object 21 in the viewer space 45, the object 21 projects a left image 22 in right side of the projection plane 44 to be observed by the left eye 42. The object 11 projects a right image 23 in left side of the projection plane 44 to be observed by the right eye 43. This is the principle of producing left image and right image of stereo 3D image.
As shown in FIG. 5, the computer 3D graphics engine obtains a left image 51 and a right image 52 by shifting the projection image of an object rightward or leftward. Since the 3D graphics engine clips the image beyond the projection section, the left eye image 51 has a noise region in its right side, and the right eye image 52 has a noise region in its left side when the object displayed in monitor (positive parallax). When the left image 51 and the right image 52 are alternately displayed on the monitor, the display shows a noise region 57, 58 respectively in its left and right side.
Therefore, there exists a need for removing the a first mask region 61 in the left side of said stereo 3D image and a second mask region 62 in the right side of said stereo 3D image as shown in FIG. 6.